Hello, I'd like to propose the attached patch which changes "--best" to "--fast" in the lh_binary_tar helper. Using "--best" (the highest level of compression) can take 20% longer to complete but only provides 4-5% better compression. This performance impact can quickly be inflated when performing on platforms such as ARM. To put this in perspective, I did a few unscientific tests.
1138mb chroot directory, Intel(R) Core(TM)2 Duo CPU P8600 best: 3m26.249s, 534mb tar.gz (2m44.717s longer to complete, 45mb smaller tar.gz) fast: 0m41.532s, 579mb tar.gz (2m44.717s quicker to complete, 45mb larger tar.gz) On an ARMv7 Processor rev 1 (v7l), fast was 45 minutes faster than best for the same chroot directory. Cheers, -- Cody A.W. Somerville Software Systems Release Engineer Foundations Team Custom Engineering Solutions Group Canonical OEM Services Phone: +1-781-850-2087 Cell: +1-506-471-8402 Email: cody.somervi...@canonical.com
=== modified file 'helpers/lh_binary_tar' --- helpers/lh_binary_tar 2009-01-26 16:39:27 +0000 +++ helpers/lh_binary_tar 2009-07-31 21:42:48 +0000 @@ -48,7 +48,7 @@ if gzip --help | grep -qs '\-\-rsyncable' then tar cf binary-tar.tar binary - gzip --rsyncable --best binary-tar.tar + gzip --rsyncable --fast binary-tar.tar else tar cfz binary-tar.tar.gz binary fi
